Abstract: A method of producing paperboard and cartons made therefrom is described incorporating a waterproof or water resistant coating applied to the interior of the carton except for areas intended for gluing. A coating material (122) is applied to the surface of an applicator roll (110), and a portion of the coating material is then removed from the roll. Contact between a paperboard web (150) and the roll transfers coating material to the web, creating a coated surface except for an uncoated stripe (237). A carton blank (300) may be formed from the coated web with the uncoated portion of the carton blank cut from the uncoated stripe.

Abstract: A repulpable wet strength paperboard formed from an aqueous dispersion of cellulosic fibers treated with a temporary cationic wet strength agent and a permanent wet strength agent or a reactive internal size wherein said temporary wet strength agent and said permanent wet strength agent or size are used in combined amounts sufficient to impart wet strength to said paper yet render said paper readily repulpable.

Abstract: The invention relates to a repulpable wet strength paper containing a blended of cationic permanent and temporary wet strength agents.

Abstract: A glue bond testing apparatus for testing the glue bond at the end flaps of paperboard cartons, such as commonly used for packaging canned or bottled beverage products, is provided with a carton support which is adapted to receive an erected filled and glued carton and hold the same against movement. A gripper plate or clamp is secured to the carton end flap, the glue bond of which is to be tested. An electronic strain gauge is mounted on the apparatus with a force input rod connected to the clamp through a removable rigid connection. The electronic force gauge is slidably mounted on a pair of parallel rods for back and forth movement in a direction toward and away from the gripper plate. The carton support is arranged to support the carton to be tested at an angle to the direction of movement of the electronic force gauge so as to simulate the hand opening test of the flap.